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The subject invention relates to a system and method for controlling the temperature of a region of brain tissue.
Researchers and physicians have long recognized the consequences of reduction of body temperature in mammals, including induction of stupor, tissue damage, and death. Application of freezing and near freezing temperatures to selected tissue is commonly employed to preserve tissue and cell (e.g. sperm banks); and application of extreme cold (far below freezing) is effective for tissue ablation. However, localized cooling (not freezing) of tissue has generally been limited to the placement of an xe2x80x9cice-packxe2x80x9d or a xe2x80x9ccold compressxe2x80x9d on injured or inflamed tissue to reduce swelling and the pain associated therewith. Localized cooling of internal organs, such as the brain, has remained in large part unexplored.
For example, xe2x80x9cbrain coolingxe2x80x9d has been induced by cooling the blood supply to the brain by inserting a chilled catheter into the arteries. However, as the effects of the cold blood cannot be easily localized, the shortcomings of systemically cooling the entire blood pool are realized, and the technique become impractical. Such shortcomings include cardiac arrhythmia, immune suppression and coagulopathies.
Attempts have been made to localize cooling of the brain with wholly external devices, such as cooling helmets or neck collars. Cooling helmets appear to be ineffective at reaching depths within the brain due to insufficient cooling power. Neck collars attempt to cool blood supplies and therefore become a systemic blood cooling method and thus are subject to the same shortcomings as other systemic cooling methods.
It is therefore desirable to obtain improved devices and methods that allow for localized brain cooling without the disadvantages of the known systemic and external devices and techniques.
The subject invention advantageously provides a system and method for controlling the temperature of a blood vessel. As described herein, the device lowers the localized blood temperature of the blood vessel by enveloping the blood vessel to transfer thermal energy there between. In this manner the device can, for example, lower the localized blood temperature of the internal carotid artery to affect selective cooling of the brain.
The medical device of the subject invention controls the localized temperature of the blood vessel by surrounding the blood vessel and transferring thermal energy between the medical device and the blood vessel. The medical device includes a thermal support structure for surrounding the blood vessel, whereby the support structure is configured to control thermal energy transfer between the support structure and the blood vessel. In exemplary usage, the temperature is controlled using thermally-conductive fluid perfusion through the thermal structure surrounding an outside section of blood vessel.
In a method of use, the medical device is placed using a cut-down procedure, either sliding or placing the device under the dissected blood vessel and securing. In this way, one avoids any adjacent nerves, and assures that other peripheral or peri-vascular structures are insulated. Once secured, the thermally-conductive fluid enters the thermal transfer region, thereby effecting the localized blood temperature of the blood vessel. For example, the localized temperature of the blood vessel is lowered by a perfusion of thermally-conductive fluid having a temperature lower then that of the blood vessel. Alternatively, the localized temperature of the blood vessel is increased by a perfusion of thermally-conductive fluid having a temperature greater then that of the blood vessel.